/Engine/Plugins/Developer/Concert/ConcertSync/ConcertSyncClient/Source/ConcertSyncClient/Public/ConcertClientLocalDataStore.h
The class documentation for an example.
template<typename T> [TConcertDataStoreResult](API\Plugins\ConcertSyncCore\TConcertDataStoreResult)< T > CompareExchange ( const [FName](API\Runtime\Core\UObject\FName) & Key, const T & Expected, const T & Desired )